Donate to Mozilla Thunderbird

Your payment details will be processed by Stripe (for credit/debit cards) or Paypal, and a record of your donation will be stored by Mozilla. Contributions go to the Mozilla Foundation, a 501(c)(3) organization based in Mountain View, California, to support Thunderbird. Mozilla reserves the right to find another use for the funds if it determines that Thunderbird is no longer furthering Mozilla’s mission.

Source: donate.mozilla.org